Usage

EveScript consists of a compiler EveScriptCompiler and an executor EveScriptExecutor.

Write a Script

An EveScript is written in the following form:

if (expression) {
  action1(...)
  action2(...)
}

where, the expression is a bool expression, and the actions are a list of “function” calls. The condition expression consists of variables, operators and constants (strings, numbers, and booleans).

Actions, variables, and operators are three types of entities that must be provided before the script can execute.

Here is a quick example (quickstart.es) for you to start script with EveScript.

if ($lightSensor < 20) {
  say("It's getting dark now!")
}

In this script, we used three entities that need to be provided when executing.

• $lightSensor: This is a variable. A variable is a custom function that is provided as a data source to the script.

• say: This is an action. An action is a custom function that will be called when the expression is true.

We will provide these entities in the Run a script section.

For more details, see EveScript Language Reference.

Compile a Script

An EveScript file (*.es) needs to be compiled before executed. This is done by calling the compile() method in the EveScriptCompiler class.

from evescript.compiler import EveScriptCompiler

with open('quickstart.es') as f:
  script = f.read()

compiler = EveScriptCompiler()
compiled_script = compiler.compile(f)

Run a Script

The compiled script can be executed with EveScriptExecutor. When instancing EveScriptExecutor, the entities (actions, operators, and variables) used in the scripts must be provided. Each entity is a function or lambda.

from evescript.executor import EveScriptExecutor

ACTIONS = {
  'say': lambda s: print(s),
}

VARIABLES = {
  '$lightSensor': lambda x: 10,
}

# Provide the actions and the variables used in the script
executor = EveScriptExecutor({
  'actions': ACTIONS,
  'variables': VARIABLES,
})

# run the first trigger
executor.run_script(compiled_script)

Since we mocked the varialbe $lightSensor to make it always returns 10, the action will be executed and will print It's getting dark now!.

Decompile a Script

Sometimes it is necessary to retrieve the script source for given compiled script. This can be done with EveScriptDecompiler. It provides a decompile method that takes a compiled script and returns the original script text.

NOTE: The decompiled script may not be identical to the original script - the whitespaces, new lines may differ, and the decompiled script will not contain any comments that may have appeared in the original script.

The following snippet shows how to decompile:

import os
import sys

from evescript.compiler import EveScriptCompiler
from evescript.decompiler import EveScriptDecompiler

script = '''
if ($lightSensor < 20) {
  say("It's getting dark now!")
}
'''

compiler = EveScriptCompiler()
compiled_script = compiler.compile(script)

decompiler = EveScriptDecompiler()
decompiled_script = decompiler.decompile(compiled_script)

print(decompiled_script)